Editing collada file with built-in UVs
Look Honestly because i would post a comment but because i don't have enough rep i have to answer, but with blender try to go into the material properties and hopefully if you got the mesh of the internet it should have different materials, just change those separate materials and modify them to suit you since they should of been already made from the owner.

 

As seen above, there should be multiple textures for that one model.

I hope this helps and i don't quite know if i completely answered your question. If you don't see the extra materials i would say it wasn't made to be compatible with blender.